The advantages of fabricating pre-hung doors have been known and utilized in the building industry and are exemplified by U.S. Pat. Nos. 3,263,723 and 4,100,611 which describe machines for preparing doors for hanging and for fabricating pre-hung doors.
Prefabrication has also been extended to the construction of certain parts of the frame which forms the door opening, such as the attachment of the individual pieces of the door jamb. In assembling the pieces of a door jamb, it is required that the stop, the sides, and the jamb be placed in the appropriate longitudinal, horizontal and vertical alignments prior to being attached. Prior devices related to door jamb assembly and the production of pre-hung doors include U.S. Pat. Nos. 3,707,256 and 4,254,895.
U.S. Pat. No. 3,707,256 relates to a machine for assembling and packaging a pre-hung interior door unit, complete with split latch and exterior trim. The machine uses an elongated horizontal bed provided with an endless chain for conveying the door and side jamb members past fixed stapling tools which staple the trim to their associated jamb members. A separate tool drives a temporary staple to hold the two sections of the jamb together. The jamb member of the pre-hung door unit is comprised of two pieces, male and female, with a tenon and mortise joint. The female halves of the hinge and latch jambs contain integral portions which extend inward toward the door opening along the length of the jamb and act as door stops. The header jamb is formed in the same fashion. These temporarily stapled door jamb assemblies are not finished but are packaged with a pre-hung door and must be separated along the tenon and mortise joint and installed in a door opening by bringing the two halves of the assembly together from either side of the door opening.
U.S. Pat. No. 4,254,895 relates to a machine for assembling a door jamb from standard mill wood pieces. The subject of the '895 patent is a machine which removes the door jamb pieces from hoppers provided for each piece type (i.e. door jamb, stop member, side member) and aligns and registers such pieces in close proximity to a fastening or stitching means (i.e. a series of nailing tools) each of which then permanently attaches the door jamb pieces by fastening the pieces at the particular location to which they are assigned. This type of machine does not easily accommodate door jamb pieces of various dimensions and cannot easily vary the number or location of the fasteners placed in the jamb.
The prior art discussed above has not facilitated the efficient, permanent assembly of finished door jambs which utilizes both a continuous longitudinal feed of the door jamb pieces, provides for the use of a minimum number of fastening stations, and allows for the convenient variation of the length of the door jamb and the number and position of attaching means (staples or nails) which are used to construct the door jamb. Also, the present invention allows for the construction of a finished door jamb from standard mill wood pieces and does not rely on jointed or otherwise pre-milled instruction.
It is therefore an object of the present invention to provide for a continuous feed machine for assembling finished door jambs.
It is also an object of the present invention to provide a door jamb machine which utilizes a minimum number of stapling stations. As opposed to that known in the prior art, the use of a minimum number of fastening stations in conjunction with a conveyancing means which passes the door jamb pieces thereby for attachment, as in the present invention, both reduces the cost and maintenance associated with a large number of fastening stations and allows for the number and position of attachment means (such as staples or nails) to be more easily varied.
Another object of the present invention is to provide for a door jamb machine which allows the length of the finished door jamb to be conveniently varied. This allows for the construction of door jambs for both the sides and the top of the door opening for door openings of any size, particularly those variations which are commonly encountered in building applications.
Still another object of the present invention is to provide a door jamb machine which can construct a finished door jamb from standard mill wood pieces. This significantly reduces the cost of raw materials. Furthermore, the present invention is distinguished over the prior art because it provides a machine capable of constructing a finished door jamb ready for installation without the necessity of the door jamb being halved and reconstructed from either side of the door opening.
These and other advantages will be apparent from the disclosure and drawings of the present invention contained herein.